Need Help on Grid Setting

Need Help on Grid Setting

I have a data grid whose number of rows are configurable. How can I configure ExtJs to grow vertically so that user do not have to scroll up or down to view the hidden row? Right now, I have to set these settings on my grid.

viewConfig: {
forceFit: false,
},
stripeRows: true,
height: 300,

If I do not specify height, the grid does not show any rows. If I specify height too big, but there are few rows, there will be empty space at the bottom of the grid.

but the grid shrink to the size that I did not see any rows. I guess that when autoHeight sets to true, ExtJx leaves it to the container to manage the grid height. And the portal container ( i am using liferay) does not do auto expand the grid here.